<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        function Fun() {
            console.log(this);
            this.name = "lili";
            var age = 18;
            this.test = function () {
                console.log(this.age);
                console.log(age);
                var age = 20;
            }
        }
        var f = new Fun();
        console.log(f);
        console.log(f.test());
    </script>
</body>

</html>